Not getting tooltip on line chart series

When I create a rad line chart series programatically and add items to the series programatically I am unable to see the active region tooltip when I run the radchart. The code I am using is as follows:
foreach (ChartSeries series in RadChart1.Series)
{
foreach (ChartSeriesItem item in series.Items)
{

Progress, Telerik, and certain product names used herein are trademarks or registered trademarks of Progress Software Corporation and/or one of its subsidiaries or affiliates in the U.S. and/or other countries. See Trademarks or appropriate markings.